Re: Add TOAST support for more system tables

Sofia Kopikova <s.kopikova@postgrespro.ru> writes:
> This patch adds TOAST support for system tables pg_class,
> pg_attribute and pg_largeobject_metadata, as they include ACL columns,
> which may be potentially large in size.

We have been around on this topic before, cf discussion leading up to
commit 96cdeae07.  Allowing toasted data in pg_class or pg_attribute
seems quite scary to me because of the potential for recursive access,
particularly during cache-flush scenarios.  (That is, you need to be
able to read those catalogs on the way to fetching a toasted value,
so how can you be sure that doesn't devolve into an infinite loop?)

I wonder whether we'd be better off shoving the ACL data out of
these catalogs and putting it somewhere else (compare pg_attrdef).

            regards, tom lane